C#中扩展StringBuilder支持链式方法-白红宇

C#中扩展StringBuilder支持链式方法

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发布时间：2019-06-11

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本篇体验扩展StringBuilder使之支持链式方法。

这里有一个根据键值集合生成select元素的方法。

private static string BuilderSelectBox(IDictionary
     
       options, string id, bool includeUnknown){    var html = new StringBuilder();    html.AppendFormat("
      ");        return html.ToString();}

以上，

html.AppendFormat("<select id=\"{0}\" name=\"{0}\">", id);

html.AppendLine();

可以对这两个语句封装，扩展StringBuilder。

改成

public static class StringBuilderExtensions{    public static StringBuilder AppendFormattedLine(this StringBuilder @this, string format, prams object[] args) => @this.AppendFormat(format, args).AppendLine();}private static string BuilderSelectBox(IDictionary
     
       options, string id, bool includeUnknown){    var html = new StringBuilder()        .AppendFormattedLine("
      ");        return html.ToString();}

以上，

if(includeUnknown)

{

html.AppendLine("\t<option>Unknown</option>");

}

可以对如上语句进行封装，继续扩展StringBuilder.

public static class StringBuilderExtensions{    public static StringBuilder AppendFormattedLine(this StringBuilder @this, string format, prams object[] args) => @this.AppendFormat(format, args).AppendLine();        public static StringBuilder AppendLineWhen(this StringBuilder @this, Func
     
       predicate, string value) =>    predicate()         ? @this.AppendLine(value)        : @this;    }private static string BuilderSelectBox(IDictionary
      
        options, string id, bool includeUnknown){    var html = new StringBuilder()        .AppendFormattedLine("
       ");        return html.ToString();}

或

public static class StringBuilderExtensions{    public static StringBuilder AppendFormattedLine(this StringBuilder @this, string format, prams object[] args) => @this.AppendFormat(format, args).AppendLine();        public static StringBuilder AppendLineWhen(this StringBuilder @this, Func
     
       predicate, string value) =>    predicate()         ? @this.AppendLine(value)        : @this;            public static StringBuilder AppendWhen(this StringBuilder @this, Func
      
        predicate, Func
       
         fn) =>    predicate()        ? fn(@this)        : @this;    }private static string BuilderSelectBox(IDictionary
        
          options, string id, bool includeUnknown){    var html = new StringBuilder()        .AppendFormattedLine("
         ");        return html.ToString();}

以上，

foreach(var opt in options)

{

html.AppendFormattedLine("\t<option value=\"{0}\">{1}</option>", opt.Key, opt.Value);

}

对遍历语句进行封装，扩展StringBuilder，最终：

public static class StringBuilderExtensions{    public static StringBuilder AppendFormattedLine(this StringBuilder @this, string format, prams object[] args) => @this.AppendFormat(format, args).AppendLine();        public static StringBuilder AppendLineWhen(this StringBuilder @this, Func
     
       predicate, string value) =>    predicate()         ? @this.AppendLine(value)        : @this;            public static StringBuilder AppendWhen(this StringBuilder @this, Func
      
        predicate, Func
       
         fn) =>    predicate()        ? fn(@this)        : @this;            public static StringBuilder AppendSequence
        
         (this StringBuilder @this, IEnumerable
         
           seq, Func
          
            fn) => seq.Aggregate(@this, fn); }private static string BuilderSelectBox(IDictionary
           
             options, string id, bool includeUnknown){ var html = new StringBuilder() .AppendFormattedLine("
            ") .ToString();}